Method and apparatus for transmitting transport channels over a physical channel of a cellular communication system

ABSTRACT

A cellular communication network node comprises signal processing logic arranged to transmit at least one direct signalling channel indicator bit. The signal processing logic, upon receipt of a message to be transmitted, sets at least one direct signalling channel indicator bit to indicate that a direct signalling channel is active in at least one unit of resource. The signal processing logic re-allocates the at least one unit of resource for use by at least one channel other than the direct signalling channel when no direct signalling channel messages are to be transmitted.

FIELD OF THE INVENTION

The field of the invention relates, in general, to a method andapparatus for transmitting transport channels over a physical channel ofa cellular communication system. In particular, but not exclusively, thefield of the invention relates to allocating channel resources within aphysical channel of a cellular communication system.

BACKGROUND OF THE INVENTION

Known cellular communication systems, such as a Universal MobileTelecommunications System (UMTS) Radio Access Network (UTRAN),standardised by the 3^(rd) Generation Partnership Project (3GPP),typically consist of a set of radio network controllers (RNCs), Node B,also known as Node-Bs, and mobile stations (MS s), also known as UserEquipment (UEs). FIG. 1 illustrates an example of a known networktopology for part of such a cellular communication system 100.

The RNCs 105 provide a connection with, for example, a Media Gateway(not shown), which acts as a translation unit between, in this case, theUMTS network and, for example, a Public Switched Telephone Network(PSTN). The RNC 105 also performs some of the higher layer processingfor the UMTS network, performing functions, such as, setting up andmanaging radio bearers, radio resource management, supporting mobility,controlling initial access of UEs to the communication system, radiolink control (RLC), etc.

The Node Bs 110 typically perform lower layer processing for thenetwork, performing such functions as Medium Access Control (MAC),formatting blocks of data for transmission and physically transmittingtransport blocks to UEs.

As can be seen in FIG. 1, Node Bs 110 are connected to an RNC 105 via aninterface (Iub) 115. This interface between a Node B 110 and an RNC 105may be a leased line, for example provided by a fixed linetelecommunications provider, a microwave link, an Ethernet cable or someother form of communication link. The Node Bs are connected wirelesslyto the UEs 120.

In order to conserve battery life, when a UE 120 is not involved inactive connections, it is known for the UE 120 to go into an idle state,whereby the UE powers down its radio frequency circuitry (RF). When a UE120 is in the idle state, it is important to allow the Node B toinitiate a connection to the UE 120, for example when there is anin-coming call for the UE 120.

In order to achieve this, it is known for a UE 120 to periodically powerup its radio circuitry in order to monitor specific channels in order todetermine whether it is required to establish a connection with thenetwork. UMTS provides two services with which a Node B is able toindicate to a specific UE 120 that it is required to establish aconnection with the network. One is termed a Paging CHannel (PCH) andthe other is termed a Forward Access CHannel (FACH). Details of theseand other services are provided in 3GPP TS 25 221 (Universal MobileTelecommunications System (UMTS); Physical channels and mapping oftransport channels onto physical channels (TDD)) and other documentsreferenced therein.

The PCH is a downlink transport channel that is used to carry controlinformation to a UE when the network does not know the specific locationof the UE, i.e. the specific Node B to which the UE is attached.

In the known art, the PCH comprises two blocks: the Paging IndicatorCHannel (PICH) and the PCH itself. The PICH comprises multiple indicatorbits. Each UE is associated with one of the indicator bits within thePICH. Accordingly, when the UE is paged by the network using the PCH,the network sets the relevant indicator bit in the PICH. When in theidle state, the UE periodically decodes the PICH to see if the indicatorbit with which it is associated has been set. If the relevant indicatorhas been set, the UE then reads the PCH.

Each UE has a unique identifier (UE-ID). When the network pages a UE, aspreviously mentioned, the network sets the relevant indicator within thePICH for that UE, and transmits the UE-ID for the UE being paged, andthe relevant message within the PCH. In this manner, since more than oneUE may be associated with an indicator bit in the PICH, the UE-IDenables a UE to determine whether the message is intended for that UE ornot. If the PCH contains the UE-ID for the UE, the UE then reads themessage, and performs the required actions. Thus, in the known art, theindicator bits are used in a paging channel to inform the UE whether itneeds to turn its radio on for reading the PCH (i.e. as a battery savingmode).

The UMTS standard dictates that the PCH (and PICH) are alwaystransmitted at a reference power level.

In a wireless communications system, the communication medium is dividedinto units of resource. A unit of resource can be a single code (e.g.UMTS FDD), a plurality of codes, a set of codes and timeslots (e.g. UMTSTDD), a set of timeslots (e.g. a TDD system) or a set of tones, tonesand symbols or tones, symbols and timeslots (e.g. an OFDM system).

The FACH is a downlink transport channel that is used to carry controlinformation to a UE when the system knows the location cell of the UE,e.g. the specific Node B to which the UE is attached. The FACH allowsshort messages to be sent from the Node B to the UE. These shortmessages are typically control type messages that are used, for example,to allocate physical resources to the UE, set up dedicated physicalchannels, etc.

The FACH is transmitted on a set of physical resources that arepre-defined and broadcast by the Node B on a Broadcast CHannel (BCH).The FACH is controlled by the RNC, which defines the codes and timeslotsthat are reserved for FACH transmissions. The RNC also reserves anamount of power headroom for the transmission of the FACH. When the FACHis transmitted, the RNC defines the power with which the FACH must betransmitted by the Node B. Power headroom is the amount of power thatthe RNC reserves for allocation of FACH resources. The power that is notreserved for ‘power headroom’ is allocated to the Node B to do with asit sees fit (for example scheduling HS-DSCH resource into). Thus, whenthe RNC allocates power headroom, it informs the Node B that the Node Bcannot allocate that power headroom, as the power headroom is reservedby the RNC for the RNC to allocate resource into.

Unlike the PCH (and PICH), the FACH is not required to always betransmitted, and typically is only used when a message is required to besent to a UE.

FIG. 2 illustrates a high level signal flow example 200 of animplementation for FACH transmissions. An RNC sends a ‘NODE B SETUP’message to a Node B, instructing the Node B to reserve a certain set ofcodes and timeslots for FACH transmissions. This message may alsoreserve power headroom for use by the RNC. In UMTS, the ‘NODE B SETUP’message for configuring the FACH transport channel is the ‘COMMONTRANSPORT CHANNEL SETUP’ message, sent to the Node B over the Iubinterface 115.

The Node B 110 then periodically transmits a ‘SYSTEM INFORMATION’message 210 on the Broadcast CHannel (BCH). This SYSTEM INFORMATIONmessage 210 informs UEs of the physical resources used for FACHtransmissions, such as the codes and timeslots in a Code DivisionMultiple Access (CDMA) system or the sub-carriers and timeslots in anOrthogonal Frequency-Division Multiplexing (OFDM) system. The SYSTEMINFORMATION message 210 typically also contains other broadcastinformation relevant to that cell, such as the network identity etc.

A UE 120 is able to receive the SYSTEM INFORMATION message 210, andconfigure its FACH decoding function based on the information containedwithin the SYSTEM INFORMATION message 210.

When the RNC 105 needs to send a message to a UE 120 using the FACH, theRNC sends a ‘SEND FACH’ message 215 to the Node B. In UMTS, the ‘SENDFACH’ message is carried using FACH frame protocol (FACH FP) messagesover the Iub interface 115. The SEND FACH message 215 defines thespecific code and timeslot to be used for the FACH transmission 220 fromthe Node B 110 to the UE 120, as well as the power level to be appliedto the FACH transmission, the message contents and the identity of theUE (the UE-ID) that are to be included in the FACH transmission. TheNode B 110 subsequently transmits the FACH message 220 to the UE 120, asdefined by the RNC 105 in the SEND FACH message 215.

The UE 120 decodes the FACH 220 every frame, according to the definitionof the FACH provided within the SYSTEM INFORMATION message 210. If theUE-ID in the FACH message 220 matches the identity that has beenassigned to the UE 120, the UE 120 acts on the message contents in theFACH 220.

FIG. 3 illustrates an example of a known assignment of physicalresources 300 for a single Time Division Duplex (TDD) system, and showsthat one timeslot per frame is assigned for FACH usage. As previouslymentioned, the physical resources 300 for the FACH are pre-assigned bythe RNC 105, in the NODE B SETUP message 205, and cannot be reused byother channels. Even when the FACH is lightly used, for example whenmost UEs are in a connected state, receiving data traffic on a trafficchannel, indicated as a High Speed Downlink Shared Channel (HS-DSCH) 305in FIG. 3, the FACH timeslot 310 is still required to be reserved.

As will be appreciated by a skilled artisan, the fact that the FACHtimeslot 310 is required to be reserved, particularly during light useof the FACH, is an inefficient use of physical resources. Consequently,the inventor of the present invention has recognised and appreciatedthat it is desirable for the timeslot 310 assigned to the FACH to beable to be used for other purposes when it is not required for thetransmission of FACH messages. For the example illustrated in FIG. 3,the traffic channel resources, namely the HS-DSCH resources 305,comprise seven timeslots. If the timeslot 310 reserved for FACHtransmissions could be utilised for a traffic channel during periodswhen no FACH transmissions were required to be sent, the traffic channelresources could be increased from seven timeslots to eight timeslots.This would increase the traffic channel resources by fourteen percent(14%) during those periods.

A known solution for the reuse of the FACH timeslot is for the trafficchannel resources, which for the example illustrated in FIG. 3 is in theform of the HS-DSCH 305, to be used for the transmission of FACHmessages. In this case, the information that would have been transmittedon the FACH transport channel is instead transmitted on the HS-DSCHtransport channel. In this solution the Node B 110, as opposed to theRNC 105, controls the FACH, and the FACH timeslot of FIG. 3 becomes anHS-DSCH timeslot. In this manner, in the example of FIG. 3, the HS-DSCH305 always comprises eight timeslots, as opposed to seven.

The HS-DSCH 305 is a shared channel that is controlled by the Node B110. The content of the HS-DSCH 305 is allocated via Shared ControlCHannels for the HS-DSCH (HS-SCCH) 315, which is a downlink physicalchannel that carries higher layer control information for the HS-DSCH.

The HS-SCCH 315 contains a UE-ID relating to the UE 120 for whichcontent within the HS-DSCH 305 is intended. The UE-ID ensures that onlythat UE 120 for which the content of the HS-DSCH 305 is intended decodesthe HS-SCCH 315 successfully. The HS-SCCH 315 also instructs the UE ofthose codes and timeslots that are allocated to it for the HS-DSCH 305transmission allocated to it, and the coding and modulation of theHS-DSCH 305, e.g. code rate and modulation order, such as quadraturephase shift keying (QPSK), 16-QAM (Quadrature Amplitude Modulation),etc. Having decoded the HS-SCCH 315, the UE 120 is able to decoderelevant timeslot(s) of the HS-DSCH 305 using the information containedwithin the HS-SCCH 315, and retrieve the relevant content.

When the HS-DSCH 305 is used to transmit the FACH, the codes andtimeslots that are used for the HS-SCCH 315, as well as a FACH-ID arebroadcast by the Node B, for example within the SYSTEM INFORMATIONmessage 210 illustrated in FIG. 2. UEs that are required to monitor theFACH subsequently attempt to decode the HS-SCCH 315 using the FACH-ID.If a UE 120 is successful in decoding the HS-SCCH 315 using the FACH-ID,a FACH message is present within the HS-DSCH 315.

Having decoded the HS-SCCH 315 using the FACH-ID, the UE 120 thendecodes the relevant part of the HS-DSCH 305 as allocated by the HS-SCCH315, and using the information provided within the HS-SCCH 315.

The UE-ID of the relevant UE 120 is included with the HS-DSCH 305. Ifthis matches the UE-ID of the UE 120 decoding the HS-DSCH 305, the UE120 acts on the FACH message contents in the HS-DSCH 305.

When a FACH message is to be sent to a UE 120, the RNC 105 requests theNode B 110 to send a FACH to a UE 120 with a certain message. The Node B110 then schedules the transmission of the FACH message in the HS-DSCH305, along with any traffic data that is to be sent in the HS-DSCH 305.The Node B 110 chooses the codes and timeslots that are to be used forthe HS-DSCH 305 carrying the FACH message, as well as the coding andmodulation to be applied to the HS-DSCH 305. The Node B then transmitsan HS-SCCH 315 that allocates the codes and timeslots on the HS-DSCH 305for the FACH message, along with the coding and modulation used, andencodes the HS-SCCH 315 using the FACH-ID.

When there are no requests from the RNC 105 for the Node B 110 totransmit a FACH message, the Node B is able to use all of the HS-DSCH305 resource for traffic data. In this manner, physical resources areused more efficiently, and in particular physical resources are notpermanently assigned for transmitting FACH messages, in particular whenno, or few, FACH messages are required to be transmitted.

However, a problem with this known technique for reusing the FACHtimeslot is that it requires the use of the HS-SCCH 315 and the HS-DSCH305 channels for transmitting FACH messages, as opposed to just a FACHchannel, and as such carries a penalty in terms of power consumption.

FACH messages may be transmitted to a UE 120 when the UE is in an idlestate (or alternatively in a connected state). Accordingly, the Node B110 is unaware of the state of the transmission path between itself andthe UE 120. As a result, normal power control is ineffective since theNode B 110 has no information with which to make an informed decision onthe appropriate power level to use. Consequently, the power requirementsmust initially depend on the number of bits to be transmitted, and thecoding rate, without explicit knowledge of the path loss between the UEand Node B.

A number of bits transmitted on the HS-SCCH 315 is comparable to anumber of bits that are transmitted on a traditional FACH, in the orderof 60 bits (57 bits for a 3.84 Mcps TDD HS-SCCH). The exact number ofbits to be transmitted on the FACH depends on the particularimplementation. The power requirements for HS-SCCH 315 and FACH at thestart of a connection are therefore substantially the same, due to thesimilar number of bits to be carried on each channel, for exampleapproximately 33% of the Node B transmit power.

A problem with this known technique for reusing the FACH timeslot isthat both the HS-SSCH 315 and the HS-DSCH 305 must be used in order totransmit a FACH message, each requiring approximately 33% of the Node Btransmit power, albeit in different timeslots. This is in contrast tothe traditional method of transmitting FACH messages, where using thededicated FACH timeslot only required the one timeslot. Thus, the knowntechnique for reusing the FACH timeslot requires an additional timeslotat 33% of the Node B transmit power.

A skilled artisan will appreciate that, although the reuse of the FACHtimeslot by mapping the FACH onto HS-DSCH resources provides aconsiderable improvement in the use of the physical resources, thisincrease in the power requirements is undesirable.

SUMMARY OF THE INVENTION

Accordingly, the invention seeks to mitigate, alleviate or eliminate oneor more of the abovementioned disadvantages, singly or in anycombination.

According to a first aspect of the invention, there is provided acellular communication network node comprising a transmitter operablycoupled to signal processing logic and arranged to transmit at least onedirect signalling channel indicator bit generated by the signalprocessing logic. The signal processing logic is arranged, upon receiptof a message to be transmitted, to set at least one direct signallingchannel indicator bit to indicate that a direct signalling channel isactive in at least one unit of resource. The signal processing logic isfurther arranged to reallocate the at least one unit of resource for useby at least one other channel when no message is required to betransmitted.

Thus, embodiments of the invention may allow improved use of thecommunication resource in the communication system, for example byallowing physical resource to be dynamically switched between differentchannel types.

According to an optional feature of the invention, the signal processinglogic may be arranged to generate direct signalling channel resourceinformation comprising a description of the physical resources andtransport formats applied to the direct signalling channel(s). Thus,embodiments of the invention may allow the physical resources of thedirect signalling channel to be transmitted relatively infrequently toall UEs. Thus, in this manner, a reduction in the signalling load isprovided, as compared to the classic case where the physical resourcesfor the direct signalling channel are sent whenever the directsignalling channel is allocated.

According to an optional feature of the invention, the signal processinglogic may be arranged, upon receipt of a message to be transmitted, toset the at least one direct signalling channel indicator bit in a firstframe, and to transmit the message in a second frame. For example, thesecond frame may be a next consecutive frame to the first frame. Thus,embodiments of the invention may allow the UE to have a longer time toprocess the indicator bit, thereby allowing the UE complexity to bereduced and/or to allow the UE to turn its receiver off in the timeduring which the direct signalling channel is transmitted.

According to an optional feature of the invention, the signal processinglogic may allocate a plurality of direct signalling channels to at leastone unit of resource. Thus, embodiments of the invention may allow thesystem to operate with a reduced number of direct signalling channelindicator bits. The bits that are freed up on the indicator channel maythen be used for other indication purposes (e.g. paging or E-DCHACK/NACK signalling).

According to an optional feature of the invention, the signal processinglogic may generate a single direct signalling channel indicator bit fortransmission, or a plurality of direct signalling channel indicatorbits, one for each direct signalling channel, or a number of indicatorbits for transmission, where each indicator bit corresponds to aplurality of direct signalling channels. Thus, embodiments of theinvention may allow for finer granularity control of the allocateddirect signalling channel, for example the network may allocate some ofthe resource as direct signalling channel instead of either allocatingall or none of the resource. This allows for more targeted allocation ofresource to direct signalling channels and traffic channels (e.g.HS-DSCH).

According to an optional feature of the invention, the signal processinglogic may be arranged to allocate a plurality of direct signallingchannels to a plurality of units of resource. Thus, embodiments of theinvention may allow a single indicator bit to control more than onedirect signalling channel, thus either allowing more direct signallingchannels (when the number of indicator bits that can be sent areconstrained) or reduced usage of the indicator bits.

According to an optional feature of the invention, the signal processinglogic, upon receipt of at least one message to be transmitted, may bearranged to re-allocate at least one unit of resource not required fortransmitting the one or more message, for use by at least one channelother than the direct signalling channel. Thus, embodiments of theinvention may allow better usage of the resource, for example some ofthe resource may be assigned to the direct signalling channel and someof the resource may be reassigned to the other channel when it is notneeded for the direct signalling channel. Furthermore, the usage of theresource may be more tailored to the traffic profile, if the directsignalling channel is not greatly required, but there is a lot oftraffic on the traffic channel.

According to an optional feature of the invention, the at least onedirect signalling channel may be a Forward Access Channel(s) (FACH)within a Universal Mobile Telecommunications System (UMTS) network. Forexample, the at least one direct signalling channel unit of resource maybe re-allocated for use by a High Speed Downlink Shared CHannel(HS-DSCH). Thus, embodiments of the invention may allow directapplicability to an application. In this case, for example,under-utilised FACH resource may be transferred to HS-DSCH resource,thus increasing the potential throughput of HS-DSCH.

According to an optional feature of the invention, the signal processinglogic may generate the at least one direct signalling channel indicatorbit within a Broadcast CHannel (BCH) for broadcast. For example, thesignal processing logic may locate the at least one direct signallingchannel indicator bit within a Transport Format Combination Indicator(TFCI) type field within the BCH. Furthermore, according to an optionalfeature of the invention, the signal processing logic may generate thedirect signalling channel indicator bit(s) as part of a data portion ofthe BCH for broadcast. Thus, embodiments of the invention may allowtransmission directly on the broadcast channel, thereby removing a needfor a separate indicator channel. Alternatively, when an indicatorchannel naturally exists (e.g. PICH or E-HICH), the paging or E-DCHacknowledgement capacity of those indicator channels is not reduced, asdirect signalling channel indicator bits do not replace indicator bitsthat might be required for the other functions, such as PICH or E-HICH.

According to an optional feature of the invention, the signal processinglogic may generate the at least one direct signalling channel indicatorbit within a dedicated direct signalling channel indicator channel orwithin a dedicated paging indicator channel or within a E-DCH Hybrid ARQIndicator CHannel (E-HICH) of a Universal Mobile TelecommunicationsSystem (UMTS) network. Thus, embodiments of the invention may allow areduction in usage of the broadcast channel. In this manner, anindicator channel may also be more lightly coded (than a broadcastchannel), thereby allowing for lower power/lower complexity decoding ofthe indicator channel (compared to a case where the indicator bits aresent on the broadcast channel).

In accordance with a second aspect of the invention there is provided amethod for transmitting transport channels over a physical channel of acellular communication system. The method comprises determining whetherat least one message is to be transmitted. If it is determined that atleast one message is required to be transmitted, scheduling the at leastone message for transmission in at least one unit of resource allocatedto at least one direct signalling channel, and setting at least onedirect signalling channel indicator bit for transmission. If it isdetermined that no message is to be transmitted, re-allocating at leastone unit of resource allocated for use by the at least one directsignalling channel for use by at least one channel other than the directsignalling channel. Thus, embodiments of the invention may provide amore flexible usage of resources, for example direct signalling channelresource that is under-utilised may be re-assigned to other (e.g.traffic) channels.

In accordance with a third aspect of the invention there is provided acomputer program product comprising program code for signalling in awireless communication system from a network element to a wirelesscommunication unit. The computer program product comprising program codefor setting, upon receipt of a message to be transmitted, at least onedirect signalling channel indicator bit. The program code furthercomprises code for transmitting a message in at least one unit ofresource allocated for use as a direct signalling channel, andre-allocating the at least one unit of resource allocated to the directsignalling channel for use by at least one other channel when no messageis required to be transmitted. Thus, embodiments of the invention mayallow the system to run on general purpose hardware, thus reducing cost.

In accordance with a fourth aspect of the invention there is provided awireless communication unit arranged to receive a signalling messageallocating a first set of resources in a wireless communication systemfrom a cellular communication network node. The wireless communicationunit further comprises logic for receiving a at least one directsignalling channel indicator bit on a communication channel, the atleast one direct signalling channel indicator bit allocating a directsignalling channel. The wireless communication unit further compriseslogic for modifying the wireless communication unit's first set ofresources in response to a status of the at least one direct signallingchannel indicator bit.

In the existing 3GPP system, for example, whenever any resource isapplied to FACH, resources in the FACH slot and HS-DSCH resources cannoteasily be allocated to the same UE, since the amount of resource in theFACH slot and HS-DSCH slot differ and existing signalling restrictionsmean that the same amount of physical resource has to be allocated ineach timeslot. Thus, embodiments of the invention address thislimitation and may allow the system to allocate more resource to a UE.

In this manner, in contrast to normal 3GPP operation where the samenumber of codes has to be allocated to a wireless communication unit inall of the timeslots that it is allocated due to signallingrestrictions, the wireless communication unit is signalled whether FACHis active. Advantageously, the wireless communication unit is able touse this indication to modify, for example, the HS-DSCH resourceallocation, as the wireless communication unit knows that if the FACHindicator bit was set then any HS-DSCH resources that are common to FACHresources in the FACH timeslot must be allocated to FACH and not toHS-DSCH.

In accordance with a fifth aspect of the invention there is provided amethod for resource allocation in a wireless communication system by awireless communication unit. The method employed by the wirelesscommunication unit comprises receiving by a wireless communication unita signalling message allocating a first set of resources in a wirelesscommunication system via at least one direct signalling channelindicator bit on a communication channel, the at least one directsignalling channel indicator bit allocating a direct signalling channel;and modifying the wireless communication unit's first set of resourcesin response to a status of the at least one direct signalling channelindicator bit.

These and other aspects, features and advantages of the invention willbe apparent from, and elucidated with reference to, the embodimentsdescribed hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of a known network topology for part of acellular communication system.

FIG. 2 shows a high level example of a known implementation for FACHchannel transmissions.

FIG. 3 shows an example of a known assignment of physical resources.

Embodiments of the invention will now be described, by way of exampleonly, with reference to the accompanying drawing(s), in which:

FIG. 4 shows part of a cellular communication system in accordance withembodiments of the invention.

FIG. 5 and FIG. 6 show an example of resource allocation in accordancewith embodiments of the invention.

FIG. 7 shows an example of resource allocation in accordance withembodiments of the invention.

FIG. 8 shows an example of resource allocation in accordance withembodiments of the invention.

FIG. 9 shows an example of resource allocation in accordance withembodiments of the invention.

FIG. 10 shows a flowchart of a method for transmitting transportchannels over a physical channel of a cellular communication system inaccordance with embodiments of the invention.

FIG. 11 shows a flowchart of a method for transmitting transportchannels over a physical channel of a cellular communication system inaccordance with embodiments of the invention.

FIG. 12 illustrates a typical computing system that may be employed toimplement processing functionality in accordance with embodiments of theinvention.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The following embodiments of the invention will be described in acontext of a Forward Access Channel (FACH) provided as part of aUniversal Mobile Telecommunications System (UMTS) communication network,as defined in 3GPP TS 22.146 and 3GPP TS 25.221 and other documentsreferenced therein. However, it will be appreciated by a skilled artisanthat the inventive concept described herein may be applied to any directsignalling channel, such as a paging channel, an allocation channel suchas HS-SCCH or applied to alternative comparable services.

The following embodiments of the invention will be described in acontext of timeslots, for example with respect to a TDD implementation,but the inventive concept is equally applicable to any communication‘unit of resource’, for example for non-TDD implementations. Thus,hereinafter the term timeslot in a TDD context encompasses anycommunication ‘unit of resource’ outside of a TDD domain.

In one embodiment of the invention, in contrast to the known art wherethe indicator bits are used in a paging channel to inform the UE whetherit needs to turn its radio on for reading the PCH (i.e. as a batterysaving mode), the indicator bits are used to inform the UE whether itshould be reading the resources ‘reserved’ for FACH as a FACH channel,or whether it should be ignoring those resources (for example when theyare being used for another channel such as HS-DSCH).

Referring now to FIG. 4, there is illustrated a part of a cellularcommunication network 400 according to embodiments of the invention. Thecellular communication network 400 comprises a communication networknode, which for the illustrated embodiment is in a form of a Node B(NODE B) 410, operably coupled to a radio network controller (RNC) 420,for example by way of a leased line provided by a fixed linetelecommunications provider, a microwave link, an Ethernet cable or someother form of communication link. The RNC 420 may be further operablycoupled to, for example, a Media Gateway (not shown).

The Node B 410 comprises signal processing logic 440 arranged totransmit one or more indicator bits, for example on a broadcast channel.The signal processing logic 440 is further arranged, upon receipt of aFACH message to be transmitted, for example from the RNC 420, to set atleast one of the one or more indicator bits and to transmit the FACHmessage in at least one of one or more timeslots allocated for use byone or more FACH channels. The signal processing logic 440 is stillfurther arranged to reallocate the one or more timeslots allocated tothe one or more FACH channels, for use by one or more channels otherthan the one or more FACH channels, when no FACH messages are requiredto be transmitted.

The RNC 420 may, for example by way of a ‘NODE B SETUP’ message (e.g.‘COMMON TRANSPORT CHANNEL SETUP’ in UMTS), instruct the Node B 410 thosetimeslot(s) that is/are to be allocated to the FACH channel(s), alongwith a set of channelisation codes that is reserved for the FACHchannel(s) (codes used to separate the different channels that may bepresent on a certain frequency in a Code Division Multiple Access (CDMA)system), power headroom reserved for the RNC, etc. In a context of a3GPP system, the generic expressions of ‘NODE B SETUP” and ‘SEND FACH’message may be referred to, for example, as ‘COMMON TRANSPORT CHANNELSETUP’ and ‘FACH frame protocol’.

Accordingly, the Node B 410 may comprise a memory element 450, in whichthe Node B 410 stores the settings provided by the RNC 420.

Alternatively, the Node B 410 may define which timeslot(s) are to beallocated to the FACH channel, along with a set of channelisation codesthat are reserved for the FACH channel(s), power assigned to Node B FACHtransmissions etc. The Node B may then inform the RNC of thesedefinitions.

The signal processing logic 440 of the Node B 410 is arranged totransmit, upon receipt of a FACH message transmitted from the RNC 420,the one or more indicator bits within, for example, the broadcastchannel. In this manner, by monitoring the channel carrying indicatorbits, e.g. the broadcast channel, the UE 430 is able to determinewhether there is a FACH message. If there is no indicator bit set, theUE 430 is able to power down its radio circuitry until the next time thechannel carrying indicator bits is scheduled to be transmitted. If thereis a FACH message, the UE 430 is able to read the contents of the FACHchannel, and determine whether, or not, the message is intended foritself, as described in greater detail below.

Referring now to FIG. 5, there is illustrated an example of resourceallocation in accordance with embodiments of the invention, where a FACHmessage is required to be transmitted. In particular, FIG. 5 illustratesa plurality of timeslots 510 within a 3.84 Mcps TDD UMTS frame.

The plurality of timeslots 510 are allocated to transport channels,which for the illustrated embodiments may comprise a Broadcast CHannel(BCH) 525, a High Speed Downlink Shared Channel (HS-DSCH) 505, a SharedControl Channel for the HS-DSCH (HS-SCCH) 515, and a Forward AccessCHannel (FACH) 520. In embodiments of the invention, one timeslot alsocarries (what will hereinafter be referred to as) an INdicator Channel(INCH) 521, carrying indicator bits. FIG. 5 is labeled in terms oftransport channels, but the skilled artisan will appreciate thattransport channels are mapped to physical channels before transmissionand that for the transport channels illustrated there is a one-to-onemapping between transport channel and physical channel. A skilledartisan will also appreciate that the timings between channels as shownin FIG. 5, and subsequent figures, are illustrative and may vary in anactual implementation of the invention.

Furthermore, the indicator bits may be sent on any channel used to sendindicator bits, which may exist on a same timeslot as the BCH (but canalso or alternatively exist on a timeslot other than that occupied bythe broadcast channel (BCH)). For example, such indicator bits may takeover some of the indicators that are used on other indicator channels(for example some of the E-HICH indicator bits would not be used forE-HICH purposes (e.g. acknowledging uplink transmissions), but would beused for transmission of FACH indicator bits instead).

Furthermore, the indicator bits may be either broadcast to all UEs in acell, or transmitted to a targeted group of one or more UEs in a cell.For example, the targeted group of UEs may be a group of UEs with aparticular capability or may be a group of UEs geographically locatedclose to the Node B. An example method of targeting a group of UEs wouldbe to mask the indicator bits with a scrambling code that is known to agroup of UEs or to transmit the indicator bits at a power level suchthat only that group of UEs is able to receive the indicator bitsreliably.

As previously mentioned, the FACH is a downlink transport channel thatis used to carry control information to a UE. The FACH allows shortmessages to be sent from the network to the UE. These short messages aretypically control type messages that are used, for example, to allocatephysical resources to the UE, set up dedicated physical channels, etc.In particular, the FACH provides a service for a network to communicatewith UEs, without having to set up dedicated physical resources.

As previously mentioned, with respect to FIG. 4, the RNC 420 mayinstruct the Node B 410 those timeslot resources that are to be reservedfor the FACH, for example by way of a ‘NODE B SETUP’ message, along withthe channelisation codes and transport formats to be applied to theFACH. Furthermore, when the network needs to send a FACH message to aUE, for example UE 430 of FIG. 4, the RNC 420 sends a message, forexample a ‘SEND FACH’ message, to the Node B 410 comprising the contentof the message, and the identity of the UE 430, such as a UE-ID forwhich the message is intended. The RNC 420 may also define othercriteria such as the specific timeslot resources to be used (from thosereserved), specific channelisation codes to be used, etc. Alternatively,the choice of timeslot resources, channelisation codes, etc. may be leftto the Node B 410, and as such the Node B 410 schedules the transmissionof FACH messages within the, or each, FACH channel 520.

The BCH is a downlink transport channel that is used to broadcast systemand cell specific information. In particular, the NODE B 410 may use theBCH 525 to transmit resource information relating to common channels(where a common channel is a channel that a plurality of UEs are meantto decode, in contrast to a dedicated physical channel, which is meantto be decoded by a specific UE). The resource information may comprisedescriptions of channelisation codes for common physical channels,timeslot resource allocations, and formats for transport channels suchas coding and modulation.

For the illustrated embodiments, the INCH 521 further comprises one ormore indicator bits, at least one of which comprises a FACH indicatorbit 522. In this manner, the resource information on BCH furthercomprises description of the at least one indicator bit within the INCH521.

The FACH indicator bit is used to indicate whether a FACH channel towhich it relates is ‘active’. Thus, for the embodiments illustrated inFIG. 5, the FACH indicator bit 522 is used to indicate whether the FACHis ‘active’.

When the NODE B 410 is required to send a FACH message, for examplehaving received a SEND FACH message from the RNC 420, the NODE B 410sets the FACH indicator bit 522, as illustrated in FIG. 5. The NODE B410 also transmits the FACH message within the FACH timeslot, along withthe identity of the UE, for example the UE-ID, for which the message isintended.

In this manner, a UE 430 attached to the NODE B 410, is able todetermine whether there is a FACH message by monitoring the INCH 521,and in particular by reading the FACH indicator bit 522. Upon reading aset FACH indicator bit, the UE 430 determines that the NODE B 430 istransmitting a FACH message, and using the resource information beingtransmitted in the BCH 525, is able to decode the FACH message. If theidentity of the UE 430 matches the identity transmitted within the FACHmessage, the UE 430 acts on the message content.

Referring now to FIG. 6 there is illustrated the resource allocation ofFIG. 5, where no FACH message is required to be transmitted. As the NODEB 410 has no FACH message to transmit, the FACH indicator bit 522 in theINCH 521 is not set. In this manner, a UE 420 attached to the NODE B410, for example UE 430, is able to determine that the NODE B 110 is nottransmitting a FACH message, by reading the FACH indicator bit 522, andaccordingly the UE does not attempt to decode HS-DSCH resource as FACH.This may allow the UE to conserve battery power and avoids the UEincorrectly decoding HS-DSCH as FACH, thus improving reliability of theFACH transmission.

As will be appreciated by a skilled artisan, since the NODE B 410 is nottransmitting a FACH message, the timeslot allocated to the FACH 520 isfree. Therefore, in accordance with embodiments of the invention, theNODE B 410 is arranged to reallocate the FACH timeslot 520 for use by achannel other than the FACH, when no FACH message is required to betransmitted.

For the illustrated embodiments, the FACH timeslot 520 is reallocatedfor use by the HS-DSCH 505. The HS-DSCH 505 is a shared channel, thecontent and physical resources of which are allocated via the HS-SCCH515, which is a downlink physical channel that carries controlinformation for the HS-DSCH 505. A skilled artisan will appreciate that,although the HS-SCCH 515 is illustrated herein as occupying an entiretimeslot, the HS-SCCH 515 may be multiplexed with other channels.

As previously mentioned, when the NODE B 410 is not transmitting a FACHmessage, it reallocates the FACH timeslot 520 for use by anotherchannel, which for the illustrated embodiments is the HS-DSCH 505.

In this manner, when a FACH message is not being transmitted, theresources available to the HS-DSCH 505 can be expanded from, for theillustrated embodiments, seven timeslots to eight, an increase ofapproximately 14%. Thus, embodiments of the invention provide a moreefficient use of physical resources, as compared with traditionaltechniques for providing services, such as that of FACH in traditionalcellular communication systems.

Furthermore, unlike for the known solution for reusing the FACH timeslotdescribed above, as the HS-DSCH 505 and HS-SCCH 515 are not used fortransmitting FACH messages, these two channels do not each require asignificant proportion (e.g. approximately 33%) of the Node B transmitpower when a FACH message is to be transmitted. Rather, only the FACH,when a FACH message is being transmitted, requires 33% of the Node Btransmit power.

Thus, an embodiment of the invention may provide an advantage of a moreefficient use of physical resources, whilst substantially avoiding anincrease in power requirements.

For the embodiments illustrated in FIG. 5 and FIG. 6, the FACH indicatorbit 522 is illustrated as indicating 523 a state of the FACH within thesame frame. A skilled artisan will appreciate that, for some UEimplementations, this may not be feasible due to the processingrequirements this would place on the UE.

Referring now to FIG. 7, there is illustrated an example of resourceallocation in accordance with embodiments of the invention. In the sameway as for the embodiments illustrated in FIG. 5 and FIG. 6, timeslots710 within a frame are allocated to a BCH 725, HS-DSCH 705, HS-SCCH 715,FACH 720, INCH 721, etc.

For the embodiments illustrated in FIG. 7, the INCH 721 comprises aplurality of indicator bits, one of which, for the illustratedembodiments, is in the form of a FACH indicator bit 722, which indicatesthe state of the FACH 720 in a subsequent frame of the physical channel.For the illustrated embodiments, the FACH indicator bit 722 in frame ‘n’indicates 723 the state of the FACH 720 within the next consecutiveframe, frame ‘n+1’. Thus, in FIG. 7, the FACH indicator bit 722 in frame‘n’ is set, and thereby indicates that the FACH 720 is active in frame‘n+1’. In this manner, the processing requirements placed on a UE 430are reduced, since the UE 430 is provided more time in which to prepareto decode the FACH 720 if the FACH 720 is active. As illustrated, theHS-SCCH 715 may also relate 716 to the HS-DSCH 705 in the nextconsecutive frame.

Referring now to FIG. 8, there is illustrated an example of resourceallocation in accordance with embodiments of the invention. For theembodiments illustrated in FIGS. 5 to 7, a single FACH indicator bit isused to indicate a state of a single FACH, and the FACH is allocated anentire timeslot within the physical channel. A skilled artisan willappreciate that a NODE B may be arranged to provide more than one FACH,and that the plurality of FACHs may be allocated to one or moretimeslots.

For the embodiments illustrated in FIG. 8, four FACH channels areallocated to a single timeslot, and the FACH indicator bit 822 indicates823 whether at least one of the FACH channels is active. In this manner,if the NODE B is required to transmit one or more FACH messages, theNODE B sets the FACH indicator bit 822, and transmits the one or moreFACH messages in one or more FACH channels 820 within the allocatedtimeslot. In this manner, a UE is able to determine whether a FACHmessage is to be transmitted by reading the FACH indicator bit 822 inthe INCH 821. If the FACH indicator bit 822 is set, the UE then decodesthe FACH timeslot and reads each of the four FACH channels therein todetermine whether the one or more transmitted FACH messages are intendedfor itself.

If the NODE B is not required to transmit a FACH message, the NODE Bsets the FACH indicator bit 822 to ‘inactive’, and reallocates the FACHtimeslot for use by another transport channel, for example the HS-DSCH805.

Referring now to FIG. 9, there is illustrated an example of resourceallocation in accordance with embodiments of the invention. As in theembodiment illustrated in FIG. 8, four FACH channels are allocated to asingle timeslot. However, for the embodiments illustrated in FIG. 9, theINCH 921 comprises a plurality of FACH indicator bits 922. For theillustrated embodiments, the INCH 921 comprises four FACH indicator bits922, each FACH indicator bit 922 relating to one of the FACH channels920.

In this manner, when the NODE B receives one or more FACH messages to betransmitted, the NODE B schedules transmission of the one or more FACHmessages in one or more of the FACH channels 920, and sets one or moreof the FACH indicator bits 922, to indicate those FACH channels 920 thatare active.

Thus, FIG. 9 illustrates a case where the NODE B is required to transmittwo FACH messages. Accordingly, the NODE B has set two of the FACHindicator bits 922, and transmits the FACH messages within the twocorresponding FACH channels 920. As will be appreciated by a skilledartisan, for the embodiments illustrated in FIG. 9, only two out of fourof the FACH channels 920 within the FACH timeslot are used. Accordingly,and in accordance with an embodiment of the invention, the NODE Bre-allocates the timeslot resource for those FACH channels not requiredfor transmitting FACH messages, for use by another transport channel,such as the HS-DSCH 905. In this manner, even when the NODE B isrequired to transmit FACH messages, free resource within the FACHallocated timeslot may be reused for other channels.

In the embodiments shown in FIG. 9, where a timeslot is partially usedby FACH, a UE that is allocated HS-DSCH may advantageously modify itsresource allocation based on the status of the FACH indicator bit. Forexample, if the UE is allocated all eight timeslots and all sixteencodes on HS-DSCH 905, and the FACH indicator bit is set, the UE mayunderstand that in the FACH timeslot 920 it is actually allocated areduced number of HS-DSCH codes. This is in contrast to the existingoperation in 3GPP, where the same number of codes has to be allocated toa UE in all of the timeslots that it is allocated, due to signallingrestrictions. However, in accordance with embodiments of the invention,the UE is signaled whether the FACH is active. Advantageously, the UE isable to use this indication to modify the HS-DSCH resource allocation(as the UE understands that if the FACH indicator bit was set, then theUE cannot be allocated all of the resource in the FACH timeslot as thatresource is allocated elsewhere as FACH).

For the various embodiments illustrated and described herein, a singletimeslot has been allocated for FACH channels. However, a skilledartisan will appreciate that more than one timeslot may be allocated forFACH channels. Accordingly, and in accordance with an embodiment of theinvention, where more than one timeslot is allocated for FACH channels,the one or more timeslots may, individually or collectively, and as awhole or partly, be re-allocated for use by other channels when notrequired for the transmission of FACH messages.

Referring now to FIG. 10, there is illustrated a flow chart 1000 of amethod for transmitting transport channels over a physical channel of acellular communication system in accordance with embodiments of theinvention.

The method starts at block 1010 and moves to block 1020, where it isdetermined whether a FACH message is required to be transmitted, forexample whether a ‘SEND FACH’ command has been received from an RNC.

If it is determined that a FACH message is required to be transmitted,the method moves on to block 1030, where the FACH message(s) to betransmitted is/are scheduled for transmission in one or more timeslotsallocated to one or more FACH channels. The method then moves on toblock 1050.

Referring back to block 1020, if it is determined that no FACH messageis required to be transmitted, the method moves on to block 1040, wherethe timeslot(s) allocated to the one or more FACH channels arere-allocated for use by one or more channels other than the one or moreFACH channels. The method then moves on to block 1050.

In block 1050, the FACH indicator bit is configured as required fortransmission in, for example a broadcast channel or indicator channel,indicating whether the FACH is active, e.g. a FACH message is to betransmitted, or not. That is to say, if a FACH message is to betransmitted, the FACH indicator bit is set (e.g. transmitted as a logic‘1’), whereas if a FACH message is not to be transmitted, the FACHindicator bit is not set (e.g. transmitted as a logic ‘0’ oralternatively the FACH indicator bit is simply not sent at all (forexample in a Discontinuous Transmission (DTX) mode)). The method thenmoves on to block 1060, where the transmission of the transport channelsis initiated. The method then returns to block 1020, as shown.

A skilled artisan will appreciate that only those blocks pertinent tothe invention have been illustrated and described in order not toobscure the inventive concept.

Referring now to FIG. 11, there is illustrated a flowchart 1100 of amethod for transmitting transport channels over a physical channel of acellular communication system, in accordance with embodiments of theinvention.

The method starts at block 1110 and moves to block 1120, where it isdetermined whether a FACH message is required to be transmitted. If itis determined that one or more FACH messages are required to betransmitted, the method moves on to block 1130, where the one or moreFACH message(s) is/are scheduled for transmission within the allocatedtimeslot(s).

The method then moves on to block 1140, where it is determined whetherresources allocated for FACH messages are free for use by otherchannels. If it is determined that no FACH resources are free in block1140, the method moves on to block 1160. However, if it is determinedthat FACH resources are free, the method moves on to block 1150.

Referring back to block 1120, if it is determined that no FACH messagesare required to be transmitted, the method moves on to block 1150, whereresources allocated for FACH messages that are not required for thetransmission of FACH messages are re-allocated for use by otherchannels.

The method then moves to block 1160, where the, or each, FACH indicatorbit is configured as being required within a broadcast channel orindicator channel, indicating whether the FACH is active, e.g. a FACHmessage is to be transmitted, or not. The method then moves on to block1170, where the transmission of the transport channels is initiated. Themethod then returns to block 1120.

A skilled artisan will appreciate that only those blocks pertinent tothe invention have been illustrated and described in order not toobscure the inventive concept.

For the various embodiments hereinbefore described, the, or each,indicator bit has been described as being provided within an indicatorchannel. Alternatively the indicator bits may be sent on the BCH orother channel. By way of example, the indicator bit(s) may be sentwithin a Transport Format Combination Indicator (TFCI) type field withinthe BCH, wherein the TFCI field is a field that is separately encoded todata traffic to which it relates. As another example, the indicator bitsmay be sent in the data portion of the BCH or other channel.

In an embodiment of the invention, the indicator bit(s) may be providedwithin a dedicated indicator channel. The indicator bits may also betransmitted as repetition encoded bits, or alternatively they may bemore robustly encoded, such as jointly convolutionally encoded.

Alternatively, indicator bits may be transmitted within an indicatorchannel along with other indicator bits. For example indicator bits fromthe PICH (Paging Indicator CHannel) or E-HICH (E-DCH Hybrid ARQIndicator CHannel) channels may be reassigned as FACH indicator bits.

While the invention has been described in terms of particularembodiments and illustrative figures, those of ordinary skill in the artwill recognize that the invention is not limited to the embodiments orfigures described. Although embodiments of the present invention aredescribed, in some instances, using UMTS terminology, those skilled inthe art will recognize that such terms are also used in a generic senseherein, and that the present invention is not limited to such systems.

Those skilled in the art will recognize that the operations of thevarious embodiments may be implemented using hardware, software,firmware, or combinations thereof, as appropriate. For example, someprocesses can be carried out using processors or other digital circuitryunder the control of software, firmware, or hard-wired logic. (The term‘logic’ herein refers to fixed hardware, programmable logic and/or anappropriate combination thereof, as would be recognized by one skilledin the art to carry out the recited functions.) Software and firmwarecan be stored on computer-readable media. Some other processes can beimplemented using analog circuitry, as is well known to one of ordinaryskill in the art. Additionally, memory or other storage, as well ascommunication components, may be employed in embodiments of theinvention.

FIG. 12 illustrates a typical computing system 1200 that may be employedto implement processing functionality in embodiments of the invention.Computing systems of this type may be used in the NodeB (in particular,the scheduler of the NodeB), core network elements, such as the GGSN,and RNCs, for example. Those skilled in the relevant art will alsorecognize how to implement the invention using other computer systems orarchitectures. Computing system 1200 may represent, for example, adesktop, laptop or notebook computer, hand-held computing device (PDA,cell phone, palmtop, etc.), mainframe, server, client, or any other typeof special or general purpose computing device as may be desirable orappropriate for a given application or environment. Computing system1200 can include one or more processors, such as a processor 1204.Processor 1204 can be implemented using a general or special purposeprocessing engine such as, for example, a microprocessor,microcontroller or other control logic. In this example, processor 1204is connected to a bus 1202 or other communications medium.

Computing system 1200 can also include a main memory 1208, such asrandom access memory (RAM) or other dynamic memory, for storinginformation and instructions to be executed by processor 1204. Mainmemory 1208 also may be used for storing temporary variables or otherintermediate information during execution of instructions to be executedby processor 1204. Computing system 1200 may likewise include a readonly memory (ROM) or other static storage device coupled to bus 1202 forstoring static information and instructions for processor 1204.

The computing system 1200 may also include information storage system1210, which may include, for example, a media drive 1212 and a removablestorage interface 1220. The media drive 1212 may include a drive orother mechanism to support fixed or removable storage media, such as ahard disk drive, a floppy disk drive, a magnetic tape drive, an opticaldisk drive, a compact disc (CD) or digital video disk (DVD) read orwrite drive (R or RW), or other removable or fixed media drive. Storagemedia 1218 may include, for example, a hard disk, floppy disk, magnetictape, optical disk, CD or DVD, or other fixed or removable medium thatis read by and written to by a media drive. As these examplesillustrate, the storage media 1218 may include a computer-readablestorage medium having stored therein particular computer software ordata.

In alternative embodiments, information storage system 1210 may includeother similar components for allowing computer programs or otherinstructions or data to be loaded into computing system 1200. Suchcomponents may include, for example, a removable storage unit 1222 andan interface 1220, such as a program cartridge and cartridge interface,a removable memory (for example, a flash memory or other removablememory module) and memory slot, and other removable storage units 1222and interfaces 1220 that allow software and data to be transferred fromthe removable storage unit 1218 to computing system 1200.

Computing system 1200 can also include a communications interface 1224.Communications interface 1224 can be used to allow software and data tobe transferred between computing system 1200 and external devices.Examples of communications interface 1224 can include a modem, a networkinterface (such as an Ethernet or other NIC card), a communications port(such as for example, a universal serial bus (USB) port), a PCMCIA slotand card, etc. Software and data transferred via communicationsinterface 1224 are in the form of signals which can be electronic,electromagnetic, optical or other signals capable of being received bycommunications interface 1224. These signals are provided tocommunications interface 1224 via a channel 1228. This channel 1228 maycarry signals and may be implemented using a wireless medium, wire orcable, fiber optics, or other communications medium. Some examples of achannel include a phone line, a cellular phone link, an RF link, anetwork interface, a local or wide area network, and othercommunications channels.

In this document, the terms ‘computer program product’‘computer-readable medium’ and the like may be used generally to referto media such as, for example, memory 1208, storage device 1218, orstorage unit 1222. These and other forms of computer-readable media maystore one or more instructions for use by processor 1204, to cause theprocessor to perform specified operations. Such instructions, generallyreferred to as ‘computer program code’ (which may be grouped in the formof computer programs or other groupings), when executed, enable thecomputing system 1200 to perform functions of embodiments of the presentinvention. Note that the code may directly cause the processor toperform specified operations, be compiled to do so, and/or be combinedwith other software, hardware, and/or firmware elements (e.g., librariesfor performing standard functions) to do so.

In an embodiment where the elements are implemented using software, thesoftware may be stored in a computer-readable medium and loaded intocomputing system 1200 using, for example, removable storage drive 1212or communications interface 1224. The control logic (in this example,software instructions or computer program code), when executed by theprocessor 1204, causes the processor 1204 to perform the functions ofthe invention as described herein.

It will be appreciated that, for clarity purposes, the above descriptionhas described embodiments of the invention with reference to differentfunctional units and processors. However, it will be apparent that anysuitable distribution of functionality between different functionalunits, processors or domains may be used without detracting from theinvention. For example, functionality illustrated to be performed byseparate processors or controllers may be performed by the sameprocessor or controller. Hence, references to specific functional unitsare only to be seen as references to suitable means for providing thedescribed functionality, rather than indicative of a strict logical orphysical structure or organization.

Although the invention has been described in connection withembodiments, it is not intended to be limited to the specific form setforth herein. Rather, the scope of the present invention is limited onlyby the claims. Additionally, although a feature may appear to bedescribed in connection with particular embodiments, one skilled in theart would recognize that various features of the described embodimentsmay be combined in accordance with the invention. In the Claims, theterm ‘comprising’ does not exclude the presence of other elements orsteps.

Furthermore, although individually listed, a plurality of means,elements or method steps may be implemented by, for example, a singleunit or processor. Additionally, although individual features may beincluded in different claims, these may possibly be advantageouslycombined, and the inclusion in different claims does not imply that acombination of features is not feasible and/or advantageous. Also, theinclusion of a feature in one category of claims does not imply alimitation to this category, but rather the feature may be equallyapplicable to other claim categories, as appropriate.

Furthermore, the order of features in the claims does not imply anyspecific order in which the features must be performed and in particularthe order of individual steps in a method claim does not imply that thesteps must be performed in this order. Rather, the steps may beperformed in any suitable order. In addition, singular references do notexclude a plurality. Thus, references to ‘a’, ‘an’, ‘first’, ‘second’,etc. do not preclude a plurality.

It will be understood that the method and apparatus for transmittingtransport channels over a physical channel of a cellular communicationsystem described above provides, by way of example only, at least theadvantages of a more efficient use of physical resources, whilstsubstantially avoiding an increase in power requirements.

1. A cellular communication network node comprising a transmitteroperably coupled to signal processing logic and arranged to transmit atleast one direct signalling channel indicator bit generated by thesignal processing logic; wherein the signal processing logic is operableto, upon receipt of a message to be transmitted, set at least one directsignalling channel indicator bit to indicate that a direct signallingchannel is active in at least one unit of resource; and the signalprocessing logic is further operable to reallocate the at least one unitof resource for use by at least one other channel when no message is tobe transmitted.
 2. The cellular communication network node of claim 1wherein the signal processing logic is operable to generate directsignalling channel resource information comprising a description of thephysical resources and transport formats applied to the directsignalling channel.
 3. The cellular communication network node of claim1 wherein the signal processing logic is operable to, upon receipt of amessage to be transmitted, set the at least one direct signallingchannel indicator bit in a first frame and transmit the message in asecond frame.
 4. The cellular communication network node of claim 3wherein the second frame is a next consecutive frame to the first frame.5. The cellular communication network node of claim 1 wherein the signalprocessing logic is operable to allocate a plurality of directsignalling channels to the at least one unit of resource.
 6. Thecellular communication network node of claim 5 wherein the signalprocessing logic is operable to generate a single direct signallingchannel indicator bit for transmission.
 7. The cellular communicationnetwork node of claim 5 wherein the signal processing logic is operableto generate a plurality of direct signalling channel indicator bits, onebit for each direct signalling channel.
 8. The cellular communicationnetwork node of claim 5 wherein the signal processing logic is operableto generate at least one indicator bit for transmission, wherein eachindicator bit corresponds to a plurality of direct signalling channels.9. The cellular communication network node of claim 5 wherein the signalprocessing logic, upon receipt of at least one message to betransmitted, is operable to re-allocate at least one unit of resourcenot required for transmitting the at least one message, for use by atleast one channel other than the direct signalling channel.
 10. Thecellular communication network node of claim 1 wherein the signalprocessing logic is operable to allocate a plurality of directsignalling channels to a plurality of units of resource.
 11. Thecellular communication network node of claim 1 wherein the at least onedirect signalling channel is a Forward Access Channel(s) (FACH) within aUniversal Mobile Telecommunications System (UMTS) network.
 12. Thecellular communication network node of claim 11 wherein the at least oneunit of resource is re-allocated for use by a High Speed Downlink SharedCHannel (HS-DSCH).
 13. The cellular communication network node of claim11 wherein the signal processing logic is operable to generate the atleast one direct signalling channel indicator bit within a BroadcastCHannel (BCH).
 14. The cellular communication network node of claim 13wherein the signal processing logic is operable to locate the at leastone direct signalling channel indicator bit within a Transport FormatCombination Indicator (TFCI) type field within the BCH.
 15. The cellularcommunication network node of claim 13 wherein the signal processinglogic is operable to generate the at least one direct signalling channelindicator bit as part of a data portion of the BCH for broadcast. 16.The cellular communication network node of claim 1 wherein the signalprocessing logic is operable to generate the at least one directsignalling channel indicator bit within at least one of: (i) a dedicateddirect signalling channel indicator channel; (ii) a dedicated pagingindicator channel of a Universal Mobile Telecommunications System (UMTS)network; or (iii) a E-DCH Hybrid ARQ Indicator CHannel (E-HICH) of aUniversal Mobile Telecommunications System (UMTS) network.
 17. A methodfor transmitting transport channels over a physical channel of acellular communication system, the method comprising: determiningwhether at least one message is to be transmitted; if at least onemessage is to be transmitted, scheduling the at least one message fortransmission in at least one unit of resource allocated to at least onedirect signalling channel; setting at least one direct signallingchannel indicator bit for transmission; and if no message is to betransmitted, re-allocating the at least one unit of resource for use byat least one channel other than the at least one direct signallingchannel.
 18. A computer program product comprising program code forsignalling in a wireless communication system from a network element toa wireless communication unit, the computer program product comprisingprogram code for: setting, upon receipt of a message to be transmitted,at least one direct signalling channel indicator bit; transmitting amessage in at least one unit of resource allocated for use as a directsignalling channel; and re-allocating the at least one unit of resourcefor use by at least one other channel when no message is to betransmitted.
 19. A wireless communication unit arranged to receive asignalling message allocating a first set of resources in a wirelesscommunication system from a cellular communication network node, thewireless communication unit comprising: logic for receiving at least onedirect signalling channel indicator bit on a communication channel, theat least one direct signalling channel indicator bit allocating a directsignalling channel; logic for modifying the first set of resources inresponse to a status of the at least one direct signalling channelindicator bit.
 20. The wireless communication unit of claim 19 whereinthe direct signalling channel is a Forward Access CHannel (FACH) of a3^(rd) Generation partnership project communication system.
 21. Thewireless communication unit of claim 19 wherein the first set ofresources is allocated in a High Speed Downlink Shared Channel(HS-DSCH).
 22. A method for resource allocation in a wirelesscommunication system by a wireless communication unit, the methodcomprising: receiving by a wireless communication unit a signallingmessage allocating a first set of resources in a wireless communicationsystem via at least one direct signalling channel indicator bit on acommunication channel, the at least one direct signalling channelindicator bit allocating a direct signalling channel; and modifying thefirst set of resources in response to a status of the at least onedirect signalling channel indicator bit.